The invention relates to a device for forming and controlling the outer wrapping of packs turned out by a cigarette packaging machine, and in particular, to a device capable of verifying the correct position of the outer wrapping, i.e. the label, of crush, or American style packs of cigarettes.
The prior art embraces a cigarette packaging machine disclosed in U.S. Pat. No. 3,948,115 in the name of the same applicant, in which substantially parallelepiped packs, consisting of a stack of cigarettes enveloped in foil, are introduced singly together with a sheet of wrapping material (the label) into the radial pockets of an indexing cylindrical conveyor wheel. The labels are formed from rectangular sheets of paper exhibiting printed matter, and are designed to cover the front, back and sides of the pack and one of its two ends, thereby constituting the outer wrapping of the crush type pack.
The label sheets are supplied singly through a vertical path, substantially at a tangent to the cylindrical surface of the conveyor wheel, in such a way that each folds about a respective pack into a "U" profile when slotted into the radial pocket offered by the wheel.
Once taken up by the wheel, the two endmost strips of the label which project outward from the pocket are flattened against one side of the pack by fixed and moving folder mechanisms. Thus, the label is made to ensheath the pack carried internally of the wheel, with its two ends overlapping along one side of the parallelepiped, namely, that facing outward from the pocket.
Notwithstanding the inclusion of means for guiding and adjusting the label sheets during their passage down the vertical supply path, and of an end stop, it can happen that a sheet will not be correctly aligned with the pack at the moment of their being slotted into a pocket of the conveyor wheel. More precisely, the sheet may not be positioned with its axis exactly vertical, or may not have located against the end stop, at the moment when the pack is brought to bear.
Such defects in adjustment of the sheet, in relation to the pack, may be of an order that will occasion jamming during subsequent packaging operations, due to unwarranted creasing, or tearing of the label. In these instances, the defective packs will be removed either manually or automatically.
Where defects in adjustment of the label are of a minor order, that is, not such as will cause a jam, but sufficient to compromise appearance, the defective packs will be removed only in the event of their being singled out by the operator; examples of such minor defects would be a pack in which the overlapping label ends are not exactly parallel with the adjacent edges of the pack itself, or a pack enveloped by a label exhibiting less than perfect alignment of its printed matter in relation to the face of the pack on which it appears.
The object of the invention is that of providing a device for forming the outer wrapping of crush type cigarette packs, in which any defect in adjustment of the label is detected automatically in order to enable automatic rejection of sub-standard packs.